This invention pertains to quality control systems and methods that detect process defects in large-scale manufacturing processes, such as the manufacture of pharmaceutical dosage units, using continuous spectral imaging techniques.
Defects in pharmaceutical products can be highly dangerous, or even fatal. And even if such defects are relatively minor, such as non-uniformly sized capsules, they can result in a significant loss of goodwill by the manufacturer. It is therefore of the utmost importance to avoid such defects.
Several approaches now exist to screen pharmaceutical agents packaged in predetermined dosage units, such as capsules or tablets. These include off-line and on-line methods. Off-line methods include the testing of samples of reagents and end-products using various analytical methods. On-line methods attempt to monitor the process of manufacturing the product to detect defects as they occur.
A number of on-line screening approaches currently exist. One approach includes adding coloring agents to bulk ingredients and optically checking the shape, integrity, and color of the final product. Systems employing this approach can take a series of video images of dosage units and use image processing methods to assess the shape and color of the dosage units. Other systems employ groups of discrete optical detectors to detect different colors and infrared detectors to detect the scattering caused by structural defects. These systems can be complicated to install and maintain, and cannot guarantee a defect-free product.
Several aspects of the invention are presented in this application. These relate to improvements to process control apparatus and methods, including apparatus and methods that detect process defects in large-scale manufacturing processes, such as the manufacture of pharmaceutical dosage units, using continuous spectral imaging techniques.
Systems according to the invention are advantageous in that they can continuously test the actual composition of each dosage unit within its packaging. Such systems can therefore screen for errors in coloring of ingredients, for contamination or breakdown that occurs independent of coloring, and for other types of errors that might not otherwise be detected. And because systems according to the invention can perform their composition measurements through the end-user package walls, they can detect contamination or damage that occurs during packaging.
Performing composition analysis by comparing spectral information with libraries of known spectral signatures, allows small concentrations of potentially dangerous contaminants, such as potent toxins, to be detected. Without being correlated to a specific spectral signature, such small concentrations might have little effect on prior art process monitoring methods, and might therefore be dismissed as within an error margin.
Performing composition analysis by comparing spectral information with libraries of known spectral signatures may also allow for the detection of unexpected components. Comparing acquired spectral information with libraries of components may uncover contaminants not normally associated with the process. This may allow a manufacturer to avert hazards that arise out of unforseen circumstances, such as supplier errors or deliberate tampering.
Performing composition analysis by comparing spectral information with libraries of known spectral signatures may further allow for the detection of subtle shifts in the process. Because relative quantities of ingredients can be directly measured, a change in the ratio of these ingredients can be detected. While such changes may not warrant rejection of the products, they may allow the process to be optimized and prevent the process from drifting out of its intending operating range.
Systems according to the invention may also be advantageous in that they can allow a process engineer to select optimal process variables to monitor. By mapping selected spectral information into an image, which is then processed by an image processor, systems according to the invention can apply the image processing resources to the spectral data that correlates best to known and predicted failure modes. And because the system acquires information about a large number of wavelengths simultaneously, a system operator can try a number of different approaches to achieve the best results.